1. Field of the Invention
The present invention relates to a polarizing lens, and more particularly, to a polarizing lens with good optical characteristics that is suitable as an eyeglass lens.
2. Discussion of the Background
Polarizing lenses are widely used as eyeglass lenses to reduce the glare experienced by the human eye in daily life, sports, and the like. Generally, the polarizing nature of dichroic dyes is utilized to reduce glare. These polarizing lenses are normally fabricated by forming a polarizing layer comprising a dichroic dye on a substrate on or an orientation layer positioned on a substrate. Methods for manufacturing such polarizing lenses are disclosed in, for example, published Japanese translation of PCT international publication for patent application (TOKUHYO) No. 2008-527401 or English language family members US2006/146234A1, U.S. Pat. No. 7,625,626, US2010/028532A1, and U.S. Pat. No. 7,922,847, Japanese Unexamined Patent Publication (KOKAI) No. 2009-237361 or English language family member US2011/102892A1, WO 2008/106034, and WO 2009/029198, which are expressly incorporated herein by reference in their entirety.
As is described in above publications, a functional film is normally provided on the polarizing layer to enhance durability, impart various functions, and the like in a polarizing lens.
However, when adhesion between the polarizing layer and the functional film is poor, the functional film will sometimes separate from the main body of the lens during storage or use. Accordingly, to increase the durability of a polarizing lens, a primer layer serving as an adhesive layer enhancing adhesion between the polarizing layer and the functional film is desirably provided. In this regard, waterborne resin compositions that contain little or almost no organic solvents have been proposed in recent years as adhesive layer-forming materials (the use of organic solvents has tended to be restricted from the perspective of their effect on the environment and on the human body). The present inventors considered the fact that many dichroic dyes were water soluble and that these waterborne resin compositions would thus lend themselves well to being coated on a polarizing layer containing a dichroic dye. When the present inventors employed a waterborne resin composition to form a primer layer positioned between a polarizing layer and a functional film, it was possible to enhance adhesion between the polarizing layer and the functional film. However, in some cases, cracking and clouding (haze) occurred and optical characteristics were found to deteriorate in the polarizing layer immediately following fabrication, or during storage or use, in the polarizing lenses that were fabricated. Accordingly, the present inventors conducted extensive research. They have previously proposed the use of a waterborne resin composition to form a primer layer (water-based primer layer) with a film thickness of equal to or less than 0.5 μm as a means of preventing the occurrence of cracking of the polarizing layer (Japanese Unexamined Patent Publication (KOKAI) No. 2011-170339, which is expressly incorporated herein by reference in its entirety).
The above means proposed by the present inventors is effective for preventing the occurrence of cracking of the polarizing layer in a polarizing lens having a water-based primer layer. However, a relatively high degree of film-forming technology is required to form a thin, uniform coating film. Thus, from the perspective of manufacturing suitability and productivity, it is also desirable to prevent the occurrence of cracking in the polarizing layer in polarizing lenses having a water-based primer layer with a film thickness exceeding 0.5 μm.